In photovoltaic power generation, DC (Direct Current) arc may occur due to humidity, wire insulation corruption, wire ends loose, etc. The DC arc may produce high temperature and flame, even lead to a fire disaster. Accordingly, a photovoltaic inverter needs an arc fault detection device or a function of arc fault detection, and then informs the interrupt circuit to interrupt the DC arc.
A conventional method for arc fault detection is to detect the noise signal upon DC current at a DC side of the inverter, so as to judge whether an arc fault occurs according to a frequency domain characteristic of the DC current. However, since the inverter is a switching power device, switching actions may produce high frequency interference signals, which may lead to a misjudgment through the method for judging whether an arc fault occurs only according to the frequency domain characteristic. Further, once it is misjudged that an arc fault occurs, a protective device of the inverter may shut down the inverter, which may lead to an economic loss of the user or owner. Accordingly, it is necessary to find a method for accurately identifying an arc fault.